1) Field of the Invention
The present invention relates to an integrated circuit which includes a reconfigurable circuit and an input data controlling method for a reconfigurable circuit.
2) Description of the Related Art
Conventionally, a dynamic reconfigurable LSI is provided wherein a function can be changed over by dynamically changing a circuit configuration of a reconfigurable circuit in an operating state of the circuit.
The reconfigurable LSI includes a reconfigurable circuit wherein a plurality of computing units are arranged in an array and are interconnected by buses extending in vertical and transverse directions. The circuit configuration (network between the computing units) of the reconfigurable circuit can be changed over in a short period of time (for example, in a period of time of 1 clock to several clocks).
For example, in the reconfigurable LSI, by changing over the circuit configuration of the reconfigurable circuit, it is possible to perform an image process on one occasion but perform a process of a voice communication system on another occasion.
In such a reconfigurable LSI as described above, many functions can be implemented by one piece of hardware without providing hardware for exclusive use for the individual functions. In other words, in the reconfigurable LSI, by effectively utilizing finite resources which are determined at the point of time of fabrication of the LSI, an optimum circuit ready for many applications can be implemented.
It is to be noted that, as a result of a prior art search actually conducted, Japanese Patent Laid-Open No. 2006-18539 and a pamphlet of International Publication No. 2002/095946 have been obtained.
Incidentally, where such a simple process that the resources of the reconfigurable circuit are sufficient for the process is performed, the reconfigurable circuit may be set so as to have a predetermined circuit configuration so that the process is performed.
However, where such a complicated process that the resources of the reconfigurable circuit are insufficient for the process is performed (for example, where the data amount to be inputted is great and the throughput is high), it is necessary to dynamically vary the circuit configuration of the reconfigurable circuit. In this instance, if the input timing of the data is not controlled, then there is the possibility that the data may not be processed by the reconfigurable circuit.
On the other hand, depending upon the contents of the process, the reconfigurable circuit may be configured in a circuit configuration composed of a plurality of circuits divided spatially such that the process may be performed parallelly by the circuits. In this instance, if the configuration and the input timing of input data are not controlled, then there is the possibility that the process cannot be performed by the reconfigurable circuit.
In such an instance as just described, although, for example, mapping or the like is contrived to cope with the problem just described, it is demanded to utilize resources more efficiently and to perform mapping more readily.
Incidentally, there is a tendency to try to implement one or plural functions of an ASIC (Application Specific Integrated Circuit) using the reconfigurable technique.
Generally, the ASIC has the following characteristics.
(1) Since hardware is configured so as to be ready for a specific application, the chip size is small.
(2) Since the development cost is high, recovery of the development cost is difficult without producing in large amounts.
(3) Since the period of time for development and the lifetime of the product are long, the risk is higher where it is obliged to perform functional modification or the like during development or after shipment of products.
On the other hand, the reconfigurable LSI has a characteristic that, while it has a performance proximate to that of hardware, the function can be changed also after product shipment.